10.01 - Government Drive Proposal

Home Browse Search

July 5, 2005 * * * DRAFT' * * Page 2 of 7 Pequot Lakes Government Drive Proposal 2. We understand the City sanitary sewer and watermain improvements along Government Drive, the intersecting streets, and the adjacent alleys to be vintage 1960's, i.e. about 40 years old. We are not aware of any deficiencies in this present system. Are there extensions or replacements of the sanitary sewer and watermain systems in this area that the City wants to undertake in conjunction with this project? Any costs to be paid for from the City Sanitary Sewer and Water"enterprise" funds. 3. With existing and new building roofs, sidewalks, parking areas, streets, and other impervious surfaces, handling storm drainage along Government Drive is going to be an issue. There are no City standards for storm drainage design. In looking at other City, CSAH, and MnDOT standards, the design storm varies from 3-year to 5-year to 10-year, depending on traffic counts, speed limits, and residential or commercial uses. The higher the traffic counts and the more commercial an area, the higher the design year. For reference, a 3-year storm is about 2.8 inches over 24 hours, a 5-year storm is about 3.3 inches over 24 hours, and a 10-year storm is about 3.8 inches over 24 hours. However, if this amount of rain comes in the first hour of the 24 hour period, the design will be undersized (at least for that first hour). Another way to look at design storm frequency is from a probability perspective. Over a long period of time and data history, there is a 33% chance that a 3-year storm will be equaled or exceeded in any one year (20% for a 5-year and 10% for a 10-year). It is somewhat like pulling a slot machine handle; the probability is there the next storm too. The Industrial Park's storm sewer system is designed for a 5-year storm. Unless the Council desires differently, we recommend using a 5-year design storm. The storm drainage design will be split into two halves with CSAH 11/Main Street being the high point separating the two. For the south half, an infiltration basin will have to be located somewhere on this end to handle the discharge of stormwater. For the north half, the existing storm sewer system under the Trailside Park could possibly be used with some portions maybe requiring replacement, and property for an infiltration basin will need to be determined and recorded. Costs to be paid for from the City Storm Water Utility fund. 4. There will be two 12-foot wide through lanes, one in each direction. There will be no dedicated left turn or right turn lanes as the proposed parking will use up the width needed for such turn lanes. CADocuments and Settings\Administrator\Local Settings\Temporary Internet Files\OLKB\Draft Government Drive proposal.doc